Aircraft control system



May 24, 1949. A. G. PARKER AIRCRAFT CONTROL SYSTEM Filed July 16, 1945 4Sheets-Sheet l exi f I N VENTOR A.G.-PARKER I ATTORNEYS AIRCRAFT CONTROLSYSTEM Filed July 16, 1945 4 Sheets-Sheet 2 funulqlpllllllyly INVENTORA-G-PARKER ,Y Z% 4 m5 7%??112527 May 24, 1949. A. G. PARKER AIRCRAFTCONTROL SYSTEM 4 Shee'ts-Sheet 3 Filed July 16, 1945 INVENTQR A- G- PAR5% May 24, 1949. A. G, PARKER I 2,471,283

AIRCRAFT CONTROL SYSTEM Filed July 16, 1945 4 Sheets-Sheet 4 mvE'm'oh A-s. PARKER ATTORNEYS Patented May 24, 1949 UNITED STATES PATENT OFFICE 6Claims.

This invention relates to aircraft and the object is to provide agenerally improved aircraft control system in which motion istransmitted to ailerons or other controls through the agency of twocoordinated motion-transmitting units of the swash plate type describedin my co-pending United States application Serial No. 605,309, filedJuly 16, 1945, now Patent No. 2,438,182, issued on March 23, 1948.

In the above mentioned application I have described amotion-transmitting unit comprising a primary member supporting asecondary member consisting of an inclined disc carried by a shafthaving its ends rotatably journalled in bearings afforded by the primarymember. The disk carrying shaft extends through a yoke ring which ispivotall supported by the primary member for swingin movement about anaxis passing transversely through said shaft. The peripheral portion ofthe inclined disk is constituted by a strap ring mounted on ananti-friction bearing which holds the strap ring and the disc inco-planar relation. The strap ring is provided, at diametricallyopposite points, with trunnions which are journalled in the yoke ring sothat the strap ring is held against rotation with the disc but serves asa coupling through which the wobbling motion of the disc during rotationof the shaft is transmitted to the yoke ring to oscillate the latterabout its pivotal axis. This oscillating movement of the yoke ring isutilized to impart linear or reciprocating movement to a rod or otherdriven element connected therewith.

A further important feature of the unit described in said application inthat the primary member in which the disc-carrying shaft is journalledis movably mounted for oscillation about an axis coinciding with thepivotal axis of the yoke ring. This arrangement enables the shaft, discand yoke ring to be tilted as a unit about the common pivotal axis ofthe yoke ring and the primary member by imparting oscillating movementto said ring. This, in turn, enables reciprocating or linear movement tobe imparted to the yoke-actuated rod or other driven element by (a)oscillating the disc-carrying shaft about its central longitudinal axisor (b) oscillating the primary member to effect unitary tilting of theshaft, disc and yoke ring about an axis extending transversely throughsaid shaft.

The present invention is based on the discovery that the above mentionedand other characteristics of the motion-transmitting unit described insaid application enables it to be paired and coordinated with a similarunit to provide an ideal motion-transmitting mechanism for inclusion inan aircraft control system to operate ailerons, drooping ailerons usedas a high lift device or other aircraft controls. It may be stated,however, that when motion-transmitting units of the type described insaid application are employed for the purpose of the present inventionit is not absolutely necessary, in all cases, that the primary member inwhich the disc-carrying shaft is journalled be mounted for oscillatingmovement. In some cases it has been found possible to provide asatisfactory aircraft control system in which the primary members of thetwo coordinated motion-transmitting units are fixed in position so thatthe yoke rings are actuated solely by rotary oscillation of theassociated disc-carrying shafts. In other instances of aircraft controlsystems embodying said unit it is important that the primar members ofthe units be mounted for oscillating movement as described in saidapplication.

Proceeding now to a more detailed description of this inventionreference will be had to the accompanying drawings, in which- Fig. 1 isa diagrammatic perspective view of an aircraft control system in whichmy improved motion-transmitting units are included to control the actionof the starboard and port ailerons. In this particular control systemeach of the motion-transmitting units is of the type in which theprimary member is mounted for oscillating movement about an axis passingtransversely through the disc-carrying shaft journalled in said member.

Fig. 2 is a top plan view of one of the motiontransmitting units shownin Fig. 1. In this view the operating parts are shown in what is termedthe neutral position.

Fig. 3 is a front view of the assembly shown in Fig. 2.

Fig. 4 is a sectional view showing the mounting and assembly of thedisc-carrying shaft, the inclined disc mounted thereon and thecooperating disc actuated yoke ring.

Fig. 5 is a sectional view taken substantially along the line 55 of Fig.2 and shows the manner in which the primary member and yoke ring aremounted to swing about a common axis transverse to the axis of rotationof the disc-carrying shaft.

Fig. 6 is a diagrammatic view showing a slight modification in which therelative setting of the component parts of each unit in the neutralposition of the unit is such that theaileron raising motion of each unitis greater than its aileron 3 lowering motion thereby enabling adesirable differential action to be obtained in the operation of theailerons by said units.

Fig. 7 is a view similar to Fig. 1 but showing a slight modification inwhich the primary member of each unit is fixed in position so that theyoke ring of said unit operates solely in response to rotary movement ofthe shaft carrying the inclined yok operating disc.

In describing the drawings in detail reference will be had initially toFigs. 1 to 5 inclusive.

In the general arrangement shown in Fig. 1, two duplicatemotion-transmitting units A and B are employed for operating thestarboard and port ailerons C and D in responseto lateral movement ofthe pilot's control stick E, or in response to simultaneous operation oftwoipilot-controlled cylinder and piston devices F and G- Each of themotion-transmitting units A and B is a substantial duplicate of thatdescribed in my af-oresaid-co-pendin application. As shown more clearlyin Figs. 2 to 5 inclusive, it comprises a'bracketb including-parallelarms '6 projecting from a basegplat-e 1.; An open frame member '8;hereinafter refered to as the primary member of, themotion transmittingunit, is equipped with hollow-trunnions 9 (see Fi 5) rigidly securedthereto and extending outwardly through bearing housings I!) provided atthe free ends of bracket arms-'6. Trunnions 9 are preferably journalledin bearing housings by suitable antifriction bearings i I. Primarymember 8 is thus mounted to oscillate ;-a-bout the axis CD. A yoke ringI2 is also mounted to oscillate about axis C- -D by two supportingshafts l3 extend: ing inwardiythrough the hollow trunnions 9 asclearlyshown-in Fig.5. 7

Shafts l3 are fixed to rotate with trunnions 9 by threaded connections[4 or any other suitable means. tend into bearing housings l5 carriedbyopposite sides of yoke ring 12 and are journaled in anti-frictionbearings IS.

A shaft l8 extends through yoke ring I 2 at right angles thereto' withend portions thereof journalled in anti-friction'bearings [9 containedin bearing housings afforded by diametrically opposite portions ofprimary member 8. It will thus be seen that shaft I8 is journalled torotate about the axis A B which intersects axis C-D at right angles "andis co-planar therewith. Shaft l-8 carries a swash-plate or Wobbler disc22 which is obliquely incline-d with reference to axis AB. A strap ring24 encircles the peripheryof disc 22 and is mounted thereon by anannular anti-friction bearing 25 (Fig. 4) which retains the strap ringand disc in co-planar relation. Strap ring 24 carries diametricallyopposite trunnions 26 which lie on a common axis at right angles to theyoke-supporting shafts l3 and are journalled in bearings 21 carried byyoke ring I2. The yoke ring I2 isalso provided with ears 2'! to whichone end of an aileron operating rod 28 is secured by a pivot pin 29.

Shaft [8, disc 22 and disc-encircling strap ring 24 conjointlyconstitute which is hereinafter termed the secondary member Of themotiontransmitting unit.

One trunnion 9 of primary member 8 is ex-.

The inner-ends of shafts [3 exsame axis. Owing to the trunnionconnection between yoke ring l2 and disc-encircling strap ring 24 itwill be obvious that bodily tilting movement of disc 22 about axis CDwill result in oscillating movement of yoke ring I2 about the same axisand thereby effect linear or reciprocating movement of the aileronactuating rod 28.

One end of shaft I8 is also extended beyond the adjacent bearing housing20 and equipped with an operating lever 32 which is connected ashereinafter described to oscillate shaft I 8 about the axis AB. Thisrotary oscillation of shaft I 8 about axis AB serves, through the agencyof inclined disc 22 and strap ring 24, to oscillate yoke ring i2 aboutaxis CD and thereby impart linear or reciprocating movement to the rod28.

From the foregoing it, will be seen that linear motion may be impartedto the aileron operating rod 28 of each motion-transmitting unit by (a)turning shaft IS in either direction about axis AB or (b) tiltingprimarymember 8 and shaft IS in either direction about the axis CD. Itwill also be apparent that these movements of shaft l8 about axes AB andCD may be performed successively in any desired sequence or may beperformed simultaneously.

The motion-transmitting units A and B employed in the arrangement shownin Fig. 1 are designed so that, in the neutral position thereof, theoperating parts of each unit will be arranged as shown in Figs. 2 and 3.In this neutral condition of each unit the primary member 9 lies in ahorizontal plane, the yoke l2 lies in a vertical plane perpendicular tothe plane of the primary member and the disc 22, as viewed in Fig. 2,extends obliquely across axis AB at an angle a determined by designrequirements. The trunnions 26 are positioned directly above and belowthe intersection of the axes AB and CD.

The relative angular setting of disc 22 and lever 32 on shaft l8 ofeachunit is such that, in the neutral condition of the unit, lever 32extends downwardly from shaft, is as shown by full lines in Fig. 2. Inthe present instance the lever 30, which operates primary member '8 ofeach unit, is also shown fixed to its trunnion 9 so that it extendsupwardly from the trunnion in the neutral condition of the unit.

Lever 32 is connected, as hereinafter described, so that it may be swungupwardly from its neutral position N through a predetermined angle toeither of the predetermined aileron operating positions T or T indicatedby dotted'lines in Fig. 3. When lever 32 is swung to the left fromneutral position N toward position T the aileron operating rod 28 ismoved in the aileron raising direction indicated by the arrow R.

' When lever 32 of each'unit is moved from the neutral position N towardposition T the aileron operating rod 28 is shifted in the aileronlowering direction indicated by arrow B.

The angle through which primary member 8 of each unit may be oscillatedabout axis C-D through the agency of lever 30 and its operatingmechanism is a variable factor.

The magnitude of the angular motion imparted to the yoke ring l2 ofe'ach'unit by rotation of disc 22 is governed by'thefa'ngle at which thedisc is set in relation to its axis and this angle may be varied fordifferentapplications;

Owing to the angular arr ngement of disc 22 on shaft IB the'mOveine'ntof yckelrproceedsat varying velocity in response to constant velocitymovement of lever 32.

From the foregoing it will be seen that, in the specific arrangementshown in Figs. 1 to 5 inclusive, the angular motion imparted to yoke l2of each unit in response to movement of lever 32 from neutral positionto position T is equal to the reverse angular motion imparted to saidyoke by movement of lever 32 from neutral position N to position T. Thisis so because, in the neutral position of lever 32 and disc 22, yoke l2of each unit lies in the neutral vertical position shown in Fig. 1 andthe yoke-actuating trunnions 26 are positioned directly above and belowthe intersection of axes A-B and CD.

Reverting again to the general arrangement shown in Fig. 1, it will benoted that the aileron operating rod 28 of unit A is pivotally connectedto an arm 35 projecting upwardly from the starboard aileron C and thatthe aileron operating rod 28 of unit B is similarly connected to an arm36 projecting upwardly from the port aileron D. The two ailerons arepivoted in conventional manner to the starboard and port wings (notshown) so that each aileron is mounted to swing vertically about apivotal axis C. It has not been thought necessary to show the mountingof the brackets 5 of the two motion-transmitting units but it will beunderstood that these brackets may be attached to the wing spars or anyother suitable supporting structure,

The lever 32 of unit A is connected, through universal joint 31, rod 38and universal joint 39, to a crank arm 40 fixed to a torsion shaft 4|journalled in suitable bearings 42. Shaft 4| is connected, through crankarm 43, rod 44 and crank arm 45, to a second torsion shaft 46 journalledin bearings ll. The pilot controlled stick E is secured to torsion shaft46 by a universal joint 43 so that lateral movement of the control stickresults in rotary movement of the torsion shafts 45 and 4| in adirection dependent upon the direction of movement of the control stick.The lever 32 of unit B is connected, through universal joint 5| rod 5|and universal joint 52 and crank arm 53, to torsion shaft 4|.

Assuming that control stick E is moved laterally to port as indicated byarrow 55, the torsion shafts 45 and 4| will be rotated in the directionindicated by the arrows 56 and 51 and the rods 38 and 5| will be movedas indicated by the arrows 58 and so. This will result in the disccarrying shafts of the two motion-transmitting units being rotated sothat the aileron operating rod 28 of unit A will be moved in the aileronlowering direction indicated by the arrow 60 while the aileron operatingrod 28 of unit B will be moved in the aileron raising directionindicated by the arrow til, the extent of aileron movement in each casebeing dependent upon the extent of the lateral movement imparted to thepilots control stick E. In the present instance it will be assumed thatthe permissible range of lateral movement of the pilots control stick Eis such as to enable the lever 32 of each unit to be moved to either ofthe previously mentioned positions T and T. From the foregoing it willbe seen that, in response to lateral movement of the pilots controlstick E in either direction, one of the ailerons will be lowered and theother simultaneously'raised to control the aircraft about itslongitudinal axis and that the direction of movement imparted to eachaileron is dependent upon the direction of movement of the pilotscontrol stick.

Conditions arise where it is desirable to provide means whereby bothailerons may be drooped or returned to neutral simultaneously withoutinterfering with th ability of the pilot to operate the ailerons inopposite directions to give lateral control. According to the presentinvention this is provided for by connecting the aforesaid cylinder andpiston device F to the lever 36 of unit A and connecting the aforesaidcylinder and piston device G to the lever so of unit B. These cylinderand piston devices F and G are operated simultaneously by any suitablepilot controlled valves or other operating mechanism so that they serveto simultaneously swing the primary members 8 of the units A and B abouttheir respective axes C and D to thereby effect simultaneous operationof the two ailerons to any desired position of adjustment.

The cylinder and piston devices F and G are shown merely by way ofexample since the levers 30 of units A and B may be simultaneouslyoperated by Variable types of pilot controlled operating mechanism.

In the operation of ailerons, it is usually desirable that the aileronoperating mechanism be designed so that the lowering motion imparted toeach aileron is less than the raising motion for reasons which are wellunderstood in the art. This differential operation of the aileron is notprovided for in the arrangement shown in Figs. 1 to 7 inclusive, sincein that case the yoke [2 of each unit has the same range of movement ineither direction from its neutral position. However, this diiferentialoperation of the ailerons may be easily accomplished in accordance withthe present invention by initially assembling the component parts of thetwo units, so that, when the levers 32 are in the neutral position N(Fig. 3) the discs 22 will be in the position shown in Fig. 6 and theyokes |2 will lie in positions inclining forwardly from the neutralposition shown in Fig. 1. In this latter case the magnitude of theangular motion of each yoke i2 in the aileron lowering direction will beless than the magnitude of the angular motion in the aileron raisingdirection.

The arrangement shown in Fig. 7 is substantially the same as that shownin Fig. 1, except that the primary member 8 of each unit is fixed inposition, being formed as a rigid or integral part of a bracket 5a whichreplaces the previously mentioned bracket 5. In this case the shafts |3supporting the yoke l2 are stationary shafts extending inwardly throughopposite sides of the stationary member 8. As will be readily understoodthe yokes l2 shown in Fig. '7 operate solely in response to rotation ofthe disc carrying shaft l8 since no provision is made for tilting theshaft l8 and the primary members 8 about the previously mentioned axisC-D.

Having thus described my invention, what I claim is:

1. In an aircraft control system, the combination with a movable controlelement of means for operating said element including a motiontransmitting unit comprising a rotary shaft, an inclined disc carried byand rotatable with said shaft, a yoke through which said shaft extends,means mounting said yoke for swinging movement about an axis passingtransversely through said shaft, means interconnecting said disc andyoke so that swinging movement is imparted to the yoke by rotarymovement of the shaft and disc through a predetermined angle in eitherdirection from a neutral position, means interconnecting the yoke andthe control element so that 7 the latter is caused to operate inresponse to swinging :movement of the yoke, and means for tilting saidshaft and disc about a transverse axis coinciding with the aforesaidaxis about which the yoke is swingable.

2. loan aircraft control system, the combination with apivotally mountedaileron of operating means for swinging :said aileron to differentposidone of adjustment, said operating means ineluding a motiontransmitting unit comprising :a shaft supporting member and a yokemounted for independent swinging movement relative to each other about acommon fixed axis, a shaft extending through the yoke and having itsends rotatably Journalled in bearlngs carried by the shaft supportingmember, .a disc carried by and rotatable with said shaft, said discbeing obliquely in'clinedwith respect to the central axis of :saids'haft, means for turning said shaft through .a

predetermmed angle in either direction, :means i for swinging said shaftsupporting member through a predetermined angle in-eitheridirection tothereby tilt saidshaft and disc about the common :axis of the shaftsupporting member and yoke, means interconnecting the disc and yoke sothat the yoke is swung about its fixed axis in response to rotation ofthe shaft in either direction about its central longitudinal .axis,orswinging movement of the shaft supporting member and shaft in eitherdirection about thefixed axis of the shaft supporting member, and meansinterconneoting said yoke and aileron so that swinging movement isimparted to the aileron in response to-sw inging movement of the yoke.

3. In an aircraft control system, thecombination with a pair of controlelements mounted for swinging movement of means for operating saidelements including a separate motion transmitting unit associated withand operatively con nected to eachof said control elements, each of saidun'its comprising a shaft, meansfor rotating said shaft through apredetermined angle .in either direction from a neutral position to apredetermined :travel position comprising an inclined disc carried bysaid shaft, a yoke through which said shaft extends, means mounting saidyoke rfor swinging movement about an axis passing transversely throughsaid shaft, means intercormeotingisaidjyoke and disc so'that swingingmovement is1imparted to the yoke byrotaryimovement :of said shaft andmotion transmitting means through 'which the swinging movement ofitheyokeis transmitted to the associated con trol :element, said systembeing further characterized :iin that the "cooperating disc and yoke ofeach unit are relatively arranged so that themetion imparted to theassociated control element .hyrotation of the shaft to one of itspredetermined travel positions is less than the motion imparted to saidcontrol element by rotation of said shaft to its other predeterminedtravel position.

14 In .an aircraft control system, the combination with a plurality ofmovable rCOntIYOI elements of means for operating said elementsincluding a plurality of motion transmitting .units,-each associatedwith and operatively connected to one ofisaidicontrol elements, each ofsaid units comprising .a tiltable shaft supporting member mounted:totiltabout-a fixed axis, a shaft journalled -.in bearings carried bysaid shaft .supgporting member so that .said shaft is rotatable aboutas. central longitudinal axis at right (angles .Number to the tilt axisof the shaft supporting member, an inclined disc carried by said shaft,a yoke through which said shaft extends, means mounting said yoke forswinging movement about an axis coinciding with the axis about which theshaft supporting member is tiltable, means interconnecting said yoke anddisc so that swingi-ng movement is imparted to :the yoke by rotarymovement of said shaft or by tilting movement of "the shaft resultingfrom tilting movement of the shaft supporting member, means forsimultaneously rotating the disc-carrying shafts of said units through apredetermined angle in either direction from :a neutral to apredetermined travel position and means for simultaneously tilting theshaft supporting members of said units in either direction through apredetermined angle about their aforesaid axes to thereby effect tiltingmovement of the disc carrying shaft and the inclined disc of each unitand means conmeeting the yoke of each .unit to the associated controlelement so that the latter is operable in response to swinging movementof the yoke resulting from either rotary or tilting movement of theshaft :and the disc operatively connected to saidyoke.

5. .An aircraft control system as set forth in claim 1 which therelative setting of the disc and yoke in the neutral positioning thereofis such that the magnitude of the angular motion imparted to the yokewhen the disc is rotated through a predetermined anglein one directionis greater than the magnitude of the angular motion imparted to the yokewhen the .disc is rotated through :an equal angle in the oppositedirection.

-b. In an aircraft control system, the combination with a plurality ofmovable control elements of means for operating said elements includinga separate motion transmitting unit operatively connected to each ofsaid elements, each of said units comprising .ashaft, means for rotatingsaid shaft about its central longitudinal axis, means for :tilting saidshaft about a transverse axis and motion transmitting meansinterconnecting each shaft with its associated control element so thatmotion is imparted to the control element by either rotary or tiltingmovement of said shaft, said motion transmitting means comprising aninclined disc carried by and rotatable with said shaft, a yoke throughwhichsaid shaft extends, means interconnecting the inclined disc andyoke, means mounting said yoke for swinging move- .ment about saidtransverse axis and a motion transmitting-member connecting said yoke tothe associated-control element.

ARNOLD G. PARKER.

:RE'FERENGE S -CITED "The following references are of record in the fileof this patent:

UNITED STATES PATENTS Name Date Maltener ':May 13, 1913 Albessard .May3, 193.7 Hoekstra :Apr. 11, 1939 Couzinet Aug. 28, 19.45

FOREIGN PATENTS Country Date Germany Sept. 14, 1927 .France Oct. 30,1-939 :llurnber 1,061,917 1,621,004 "2,153j6fi7 "2,33 3,845

